Awful. I couldn't do real work on that laptop after using a B156HW01 V.3 on my Lenovo. 1280x800 is awful, and shameful for a $1000+ laptop in 2012.
I lose appreciation for how good I have it until I work on a 13" Macbook and try to do anything and have one task using up all of my screen space, and I still need more! I often multitask on my T520 and still have enough real estate to view a schematic or watch TV. I'm far too spoiled to go back to a claustrophobic display again.
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1366x768 is standard on $300 laptops, which are 1/3 the price of the Macbook Pro with lower 1280x800 resolution and slightly lower than Macbook Pros which cost six times as much.
Add $50-$100 to the base configuration of any dirt cheap laptop and you have 1600x900 or 1920x1080. Lenovo wanted an extra $250 for 1080p on mine, I bought a B156HW01 V.3 for $68 + shipping and sold the old screen for $30 on eBay. $38 for 1080p and a great quality screen.
If Apple used standard LVDS connections you'd be able to upgrade your own display without paying an arm and a leg.